It is the purpose of this project to study the mechanism of action of RNA-directed DNA-polymerase in order to use the enzyme to synthesize full-size complementary DNA and, together with other DNA polymerases, double-stranded DNA. Conditions have been found which permit complete and faithful transcription of globin mRNA into single-stranded complementary DNA and then into double stranded globin gene. BIBLIOGRPAHIC REFERENCES: Weiss, G.B., Wilson, G.N., Steggles, A.W., and Anderson, W.F.: Importance of full-size complementary DNA in nucleic acid hybridization. J. Biol. Chem. 251: 3415-3431, 1976. Weiss, G.B., and Anderson, W.F.: The problem of nuclease activity in nucleic acid hybridization reactions: theoretical considerations. Biophysical Chemistry 6: 337-344, 1977.